For example, in pharmaceuticals fields, a preparative separation-purification system employing a liquid chromatograph is used for such tasks as collecting a sample to be stored in a library. In a system disclosed in Patent Literature 1, the target components (compounds) in a sample solution are temporally separated by a liquid chromatograph. The separated target components are individually introduced into separate trap columns and temporarily captured in those columns. Subsequently, a solvent is passed through each trap column to elute the component captured in the column. The obtained solution containing the target component is collected in a container. After that, a drying process for removing the solvent and collecting the target component in a solid form is performed.
In general, the drying process is performed by heating the collected solution. However, in order to avoid alteration of the target component, the process must be performed at a considerably low temperature. Therefore, the process may require several hours, or even up to 24 hours, depending on the component. This drying process consumes the largest amount of time in the preparative separation-purification process. Accordingly, in order to reduce the entire processing time, it is essential to shorten the period of time for the drying process.
A method for solving the previously described problem is disclosed in Patent Literatures 2-5, in which the vaporization of a solvent from a solution containing a target component is promoted by nebulizing the solution by spouting a stream of gas (e.g. air or nitrogen) onto the solution while dropping the solution into a collection container.
A typical procedure of the drying process according to the method described in Patent Literatures 2-5 (which is hereinafter called the “gas-spouting vaporization-drying process”) is hereinafter described using FIGS. 8A-8D. The preparative separation-purification system in FIGS. 8A-8D includes a temperature-control block 54 for heating a collection container 53 to a predetermined temperature, a solution introduction tube 50 for introducing a solution into the collection container 53 placed in the temperature-control block 54, and a sealed tube 55 for discharging the gas introduced into the collection container 53 and the solvent vaporized within the same container 53, without allowing the gas and the solvent to leak to the outside of the system. The solution introduction tube 50 and the sealed tube 55 are integrally formed. The solution introduction tube 50 has a double-tube structure having an inner tube 50A through which the solution flows and an outer tube 50B through which the nebulizer gas flows. The collection container 53 includes a collection container body 51 and a cover part 52, with a hole formed at its center, to be attached to the upper opening of the container body 51. A doughnut-shaped cushion 52A is fitted in the upper portion of the cover part 52.
In the gas-spouting vaporization-drying process, the solution introduction tube 50 is lowered and inserted into the collection container 53 through the central hole of the cover part 52 and the cushion 52A. With this motion, the sealed tube 55 also moves downward, with its tip compressing the cushion 52A. The tip of the sealed tube 55 comes in tight contact with the cushion 52A and creates a gas-tight connection between the collection container 53 and the sealed tube 55. After that, the solution and the nebulizer gas are supplied to the inner tube 50A and the outer tube 50B, respectively. Being sheared by the stream of the nebulizer gas spouted from the outer tube 50B, the solution dropped from the tip of the inner tube 50A is broken into fine droplets (mist) and adhered to the inner wall of the collection container 53. Since the collection container 53 is previously heated by the temperature-control block 54, the solvent in the droplets adhered to the inner wall of the container turns into vapor, leaving behind the target component (solute) in a powdered form. The nebulizer gas introduced into the collection container 53 and the solvent vaporized within the same container 53 are discharged through the sealed tube 55.